Deadly 1918 flu virus lives again

Only in the lab, but even so...

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Researchers at the Centers for Disease Control (CDC) and Prevention (CDP) have, apparently without a sense of irony, reconstructed the particular strain of the flu virus that was behind the 1918 flu pandemic. That outbreak killed between 20-50m people worldwide.

The scientists rebuilt the virus using a process known as reverse genetics. The team extracted samples of the dead virus from the lung tissue of a victim of the 1918 pandemic. The body has been frozen in the Arctic tundra for 80 years. This material was then combined with modern flu viruses to resurrect the original strain.

The scientists say the work, published in the October 7 issue of Science, will help prepare for the next time a deadly flu strain breaks out in the human population, and will shed light on why the 1918 pandemic was so much more deadly than later flu pandemics in 1957 and 1968.

"By identifying the characteristics that made the 1918 influenza virus so harmful, we have information that will help us develop new vaccines and treatments," said Dr. Terrence Tumpey, a senior microbiologist at the CDC.

Lab tests have shown that the recreated batch of the virus is as lethal as the original. Lab mice and chick embryos infected with the virus died quickly, and it also grew rapidly in cultures of human lung cells. Normal flu strains don't have quite such a lethal impact, the researchers said.

A separate study has shown that the 1918 strain was originally an avian flu. At some point, it gained a mutation which allowed it to cross into the human population, and spread from person to person.

This work also revealed that the 1918 strain and the H5N1 strain of bird flu, share some mutations which allow them to spread more easily, according to reports. So far, although the H5N1 virus has killed more than fifty people since 2003, there have been no confirmed cases of human-to-human transmission.

Critics of this research argue that recreating the 1918 virus was unneccessary, and that there is now a risk that the virus could escape the lab, or that the research could be exploited by terrorist organisations.

However, scientists have long warned that another flu pandemic is inevitable, and say that work like this will mean we'll be better prepared when it happens. ®